[andyh1956]

So the text of the GM tutorial is to plumb the cooling system like a BB or a Ford.
Strange that in the text of the 350 HO engine on sheet 2 while talking cyl heads it says " The water passages are the same as the original 1955 small block design."
Then on sheet 4 "Any small block engine, regardless of year, that uses Vortec heads, will require an external coolant bypass line from the intake manifold to the 5/8" hose nipple on the water pump (passenger’s side). Suggested routing is from the 3/8 NPSF boss on intake manifold to the water pump."
Go figure.
Anyway I have a 350 Ramjet down in the shop with a std rotation long water pump on it sitting on a motor stand. It uses Vortec heads. In the morning I will go look at it & see if it has bypassed cooling & report back.